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Understanding Electromagnetic Waves

Nicholas Amendolare, April Koch
  • Author
    Nicholas Amendolare

    Nicholas Amendolare is a high school and middle school science teacher from Plymouth, Massachusetts. He has a bachelor's degree in environmental science from Worcester Polytechnic Institute and a master's degree in education from Harvard University. He has been a teacher for nine years, has written for TED-Ed, and is the founder of www.MrAscience.com.

  • Instructor
    April Koch

    April teaches high school science and holds a master's degree in education.

Learn about electromagnetic waves. Discover what electromagnetic waves are made of, and identify the seven types of waves on the electromagnetic spectrum. Updated: 02/07/2022

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EM Waves and the Electromagnetic Spectrum

Electromagnetic radiation, also known as "EM waves", is different from other forms of radiation. While the radiation involved in nuclear processes is essentially tiny particles flying through space, electromagnetic radiation is pure energy. It can be thought of as waves of electric and magnetic fields propagating throughout space at the speed of light. Or it can be thought of as little packets or energy, called "photons," flying through space in a particular direction. This wave-particle duality is one of the things that makes electromagnetic radiation so special. But how can we define electromagnetic waves or electromagnetic radiation?

Electromagnetic radiation is usually defined as a wave propagating through space, carrying energy at the speed of light. Each wave has two components, one that is electric and one that is magnetic. However, there is another way to think of electromagnetic radiation that is even simpler. Essentially, electromagnetic radiation is light. In fact, it includes seven different types of light: radio waves, microwaves, infrared light, visible light, ultraviolet light, X-rays, and gamma rays. The human eye can only detect one of the seven types, but that is a distinctly human phenomenon. Some snakes can see infrared light. Some birds can detect ultraviolet light. Electromagnetic waves are simply light, of varying frequencies, wavelengths, and intensities. All together, these seven types of light make up what is known as the electromagnetic spectrum.

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  • 0:05 Light as a Spectrum
  • 0:37 Electromagnetic Waves
  • 2:18 The Electromagnetic Spectrum
  • 4:05 Sources of EM Radiation
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A NASA diagram illustrating the full electromagnetic spectrum.

Electromagnetic spectrum

What Are Electromagnetic Waves Made of?

Electromagnetic radiation consists of electromagnetic waves, which are simply oscillations in the electric/magnetic field. Electricity and magnetism are often thought of as different phenomena, but they are actually two sides of the same coin, as James Clerk Maxwell discovered. Electromagnetic radiation is created due to periodic changes in the electromagnetic field. How quickly these changes occur dictates the frequency of the oscillation. Since these waves always travel at the speed of light, the frequency also determines the wavelength. Essentially, this determines the type of color of the light that is being produced.

In 1887, the famous Michelson-Morley experiment determined that these waves are special. Unlike ocean waves or sound waves, electromagnetic waves do require a medium in order to travel. This explains their constant speed - the speed of light - regardless of the speed or direction of their source. The exact mechanics of these waves was not well understood until Albert Einstein's theory of special relativity.

What Are the 7 Types of Waves?

Electromagnetic waves vary in both frequency and wavelength. They have been divided by scientists into seven different categories and these seven terms are what represents the different forms of electromagnetic radiation: radio waves, microwaves, infrared light, visible light, ultraviolet light, X-rays, and gamma rays.

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Frequently Asked Questions

What are the 7 electromagnetic waves in order?

The seven types of electromagnetic waves, in order from lowest frequency to highest, are as follows: radio waves, microwaves, infrared light, visible light, ultraviolet light, X-rays, and gamma rays.

What is meant by electromagnetic waves?

Electromagnetic waves are a type of radiation. They include the full spectrum from radio waves and microwaves, to visible light, to X-rays and gamma rays.

Are EM waves harmful to humans?

Determining whether electromagnetic waves are harmful to humans mainly depends on their frequency. Low-frequency waves, including radio waves, microwaves, infrared light, and visible light, are not generally harmful. But high-frequency waves like ultraviolet light, X-rays, and gamma rays can be harmful in significant amounts.

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